title: High efficiency ring-lens supercritical angle fluorescence (SAF) detection for optimum bioassay performance.
abstract: We present a polymer biochip with embedded optics which allows the detection of supercritical angle fluorescence (SAF) without losses due to total internal reflection within the substrate. The chip design comprises structured spherical and aspherical optical elements on the bottom, while the top is chemically functionalized for direct binding of biomolecules. Furthermore, this design facilitates integration in lab-on-a-chip systems with appropriate microfluidics. In the confocal optical setup an ellipsoidal mirror is used for collection of SAF light above the critical angle of the water-polymer interface, which is detected by a photon-counting detector. The work presented here represents a proof of concept for performing sensitive and rapid point-of-care testing, using this low-cost, robust and disposable optical biochip platform. The performance of the platform was validated using direct binding DNA and human IgG assays which yielded low limits of detection 10 pM for DNA and 10 pg/ml for human IgG.
authors.forename: Dirk
authors.initials: D
authors.lastname: Kurzbuch
authors.forename: Martin
authors.initials: M
authors.lastname: Somers
authors.forename: Colette
authors.initials: C
authors.lastname: McDonagh
mesh_terms: D001681:Biological Assay / Q000295:instrumentation*; D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007118:Immunoassay / Q000295:instrumentation*; D007909:Lenses; D020411:Oligonucleotide Array Sequence Analysis / Q000295:instrumentation*; D013050:Spectrometry, Fluorescence / Q000295:instrumentation*